Op, am I right in that you probably agreed & said "I'm fine" to keep the peace? You put him first above yourself & no doubt always have done?
Whereas, he, having had the discussion with his friend, should have told his friend "no, can't come, Stonymum is having surgery & I need to be home." End of discussion.
You would have been none the wiser because he'd be home looking after you.
He's not even checking in with you & he's left you with a dog!
I'm sorry OP I feel for you. Anyone, surely, would even help a friend in your situation, this is your husband.
This is no reflection on you...it's him.
Really hope the pain eases up for you & tell him when he gets back that, actually, you really have been suffering & let him pick up the slack.
Wonder what time he'll get home?
xxx